Joined on July 15, 2013
Last Post on September 15, 2013
@ September 15, 2013 7:57 PM in Taco ZVC404-EXP ProblemsThe aux switches in the zone valves were bad. I replaced the bad zone valves and now everything works perfectly.
@ July 17, 2013 1:33 PM in Taco ZVC404-EXP ProblemsI checked and there are no resistors wired in the system. Are the resistors normally wired near the valves or near the Control Panel?
@ July 16, 2013 11:37 PM in Taco ZVC404-EXP ProblemsZman
Thanks for the information. I took your advice and checked the Zone Valves. Placing a jumper wire between terminals 3 & 4 on the control panel started the circulating pump. I also checked the voltage between terminals 3 & 4 and it was +/- 12 volts. The voltage between terminals 1 & 2 is +/- 25 volts. So it appears that the Valve Actuators on the zone valves must be bad.
The Zone Valves in my system are Caleffi Z-one Z111000. Is it common to have 4 out of 8 Zone Valves fail at one time? Is my analysis correct?
@ July 15, 2013 11:56 PM in Taco ZVC404-EXP ProblemsBoth lights are turning on (Red & Yellow). The zone valves are definitely opening. They have indicators on top that show that they are open.
@ July 15, 2013 10:15 PM in Taco ZVC404-EXP ProblemsI am in Breckenridge, CO, +/- 10,000 ft. So our heater runs during the summer and we do not have or need an air conditioner. The boiler does heat our domestic hot water supply and it is working fine. It is just strange how four of the zones will turn on the circulating pump and four of them do not.
@ July 15, 2013 9:31 PM in Taco ZVC404-EXP ProblemsMy 8 Zone radiant floor heating system is controlled by 2
Taco ZVC404-EXP Controllers. One is the Master and the other one is the
Slave. The system is 3 1/2 years old and has been working fine up until last
week. I noticed that some of the zones were not heating properly.
After further inspection here is what I found:
Master: Zone 1 is not working properly. When Zone 1 calls for
heat, the boiler starts, the zone valve opens, but the circulating pump does
not run. When zone 2, 3 or 4 call for heat, the boiler starts, the zone
valve opens and the circulating pump starts running (they are working
Slave: Zones 2, 3 & 4 are not working properly. When Zone 2, 3
or 4 calls for heat, the boiler starts, the zone valve opens, but the circulating
pump does not run. Zone 1 is working properly. When zone 1 calls
for heat, the boiler starts, the zone valve open and the circulating pump
Are both controllers bad and need to be replaced? Thanks for your help.